Applying Advanced Neutron Transport Calculations for Improving Fuel Performance Codes

We present refinements of the Helium production mod el implemented in the TRANSURANUS fuel performance code. Helium is produc ed in oxide fuels by three main paths: (i) alpha decay of the actinides; (ii) (n,α) reactions; and (iii) ternary fission. In this work, the contributions due to ternary fission and the 16 O(n, α) 13 C reaction as well as some refinements in the 241 Am burn-up chain have been included in TRANSURANUS. The 16 O(n, α) 13 C cross section has been evaluated in PWR conditions by means of th e MCNP Monte Carlo code for different fuel compositions. The Monte Carlo depletion code VESTA has been used for the validation of the Helium production model. For specific PWR condition s the comparison of TRANSURANUS predictions with those of VESTA is satisfactory, an d the applied cross section library is the main source of uncertainty.